The present invention relates to music drum heads. The profile of the collar on a drum head is a critical design consideration. Many drums of nominally standard size actually vary in diameters, with the result that the bearing edge (the part of the drum shell that contacts the underside of drum head) also varies considerably with respect to diameter, angle, and accuracy.
Some vintage drums, which are highly coveted, require a drumhead with a slightly larger diameter so that the bearing edge does not interface with the curved or formed collar area of the drum head. The drum head will tune better, quicker and easier if the bearing edge contacts the flat plane of the drumhead film.
Modern drumheads are with a carefully coordinated combination of heat, pressure and time. It is a difficult task with many intricate variables, which can lead to lower yields that satisfy the desired quality threshold.